Fluid operated position selecting device

ABSTRACT

A device for selecting three different positions, which includes a hollow body having formed therein first and second bores selectively communicating with a source of pressurized fluid, a first piston having a flange slidably fitted in the first bore and a hollow extension extending from the flange and slidably fitted in the second bore, a second piston having a flange slidably fitted in the second bore and a hollow extension extending from the flange of the second piston and slidably fitted in the inner peripheral wall of the extension of the first piston, and a piston rod rigidly connected to the flange of the second piston. The positions of the second piston is shifted by selectively drawing a pressurized fluid into the first and/or second bores.

United States atent Mohri [S4] FLUID OPERATED POSITION SELECTING DEVICE[72] Inventor: Yohichi Mohri, Yokohama, Japan [73] Assignee: NissanMotor Company, Limited,

Kanagawa-ku, Yokohama, Japan [22] Filed: Nov. 3, 1970 [21] App]. No.:86,573

7.11mi VIII/ll July 4,1972

2,896,413 7/1959 Hussey ..92/62 3,353,637 11/1967 Chana ..92/52 XFOREIGN PATENTS OR APPLICATIONS 809,814 l1/l959 France ..92/52 PrimaryExaminer-Martin P. Schwadron Assistant ExaminerLeslie .lv PayneAttorney-John Lezdey [5 7] ABSTRACT A device for selecting threedifferent positions, which includes a hollow body having formed thereinfirst and second bores selectively communicating with a source ofpressurized fluid, a first piston having a flange slidably fitted in thefirst bore and a hollow extension extending from the flange and slidablyfitted in the second bore, a second piston having a flange slidablyfitted in the second bore and a hollow extension extending from theflange of the second piston and slidably fitted in the inner peripheralwall of the extension of the first piston, and a piston rod rigidlyconnected to the flange of the second piston. The positions of thesecond piston is shifted by selectively drawing a pressurized fluid intothe first and/or second bores.

1 Claim, 2 Drawing Figures PATENTEnJuL 4:912 3, 873.926 sum 2 or 2;

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. DON QCN m mm INVENTOR YOH/CH MgHR/ BY 9 6 ATTORNEY FLUID OPERATEDPOSITION SELECTING DEVICE This invention relates to a fluid pressureoperated position selecting device, and more particularly to a devicecharacterized by a novel construction adapted for selecting threedifferent positions under the control of a fluid pressure.

The device herein disclosed will find a variety of practicalapplications where continuous shifting between three different positionsis required.

In the drawings: 7

FIG. lis a sectional view of the device according to the invention; and

FIG. 2 is a schematic view of an example of the application of thedevice of FIG. 1 to an automotive automatic transmissron.

Referring now to FIG. 1, the device implementing the invention, asindicated by reference numeral 10, includes a ho]- low body 12 ofcontoured internal section. The hollow body 12 has formed therein bores14 and 16 of which the bore 14 is larger in cross section than the bore16. The bores 14 and 16 selectively communicate with a source (notshown) of a pressurized fluid through respective ports 18 and 20.

The device also includes first and second pistons 24 and 26. The firstpiston 24 has a flange 28 which is slidably fitted in the bore 14 and ahollow extension 30 which extends from the flange 28 and which isslidably fitted in the bore 16. A first sealing means or piston ring 32may preferably be provided between the outer peripheral edge of theflange 28 and the inner wall of the hollow body 12 defining the bore 14.The hollow extension 30 defines therein a cavity 34. The flange 28 hasformed therein an aperture 36 which provides communication between thebore 14 and the cavity 34.

The second piston 26 has a flange 38 slidably fitted in the bore 16 anda hollow extension 40 which extends from the flange 38 of the secondpiston 26 and which is slidably fitted in the inner peripheral wall ofthe hollow extension 30 of the first piston 24. A second sealing meansor piston ring 42 may preferably be provided between the outerperipheral edge of the flange 38 and the'inner wall of the hollow body12 defining the bore 16. Between the extensions 30 and 40 of the piston24' and 26, respectively, may also preferably be mounted a third pistonring 44. The hollow extension 40 defines therein a cavity 46.

To ensure smooth movement of the piston 26 relative to the piston 24, adrain port 22 maybe provided communicating with the substantialclearance between the extensions 30 and 40of the pistons 24 and 26,respectively, and opened to the atmosphere.

A piston rod 50 is rigidly connected to the flange 38 of the secondpiston 26. The piston rod 50 extends through the bore 16 and outwardlyfrom the hollow body 12 through a hole 48 formed in the wall of thehollow body 12. The piston rod 50 is connected at its leading end to anoperating arm 52 for carrying the relative movement of the piston rod 50to an operated device (not shown).

When both of the bores 14 and 16 communicate with the source of apressurized fluid through the ports 18 and 20, respectively, the fluidis drawn into the bores 14 and 16 to act on the flanges 28 and 38 of thefirst and second pistons 24 and 26, respectively, thereby moving thepiston 24 to its innermost position and the second piston 26 to aposition to be in contact with the flange 28 held in its innermostposition. The movement of the piston 24 is limited by a shoulder 14apartly defining the bore 14. The piston 26 in the condition has itshollow extension 40 fully admitted into the cavity 34 of the extension30 of the piston 24, and thus the movement of the piston 26 toward thebore 14 is limited by the piston 24 which is now seated on the shoulder14a. The piston 26 is in this manner held stationary in its neutral orintermediate position as shown in FIG. 1. This position of the piston 26is maintained because of the fact that the surface area of the flange 28subjected to the fluid pressure in the bore 14 is larger than thesurface area of the flange 26 subjected to the fluid pressure in thebore l6.

When the communication between the bore 14 and the source of thepressurized fluid is blocked with the bore 16 kept communicating withthe source of the pressurized fluid, the fluid is drawn only into thebore 16. The fluid pressure in the bore 16'then acts on the flange 38 ofthe second piston 26, thereby moving the piston 26 to its innermostposition.

When, in contrast, the communication between the bore 16 and the sourceof pressurized fluid is blocked with the bore 14 kept communicating withthe source of the pressurized fluid, the fluid is drawn not only intothe bore 14 but into the cavity 34 through the aperture 36. The fluidpressure passed into the cavity 34 then acts on the inner wall surfaceof the flange 38, thereby moving the second piston 26 to its outermostposition.

Thus, the piston 26 can be moved to any of its innermost, intermediateand outermost positions by selectively blocking the fluid communicationsbetween the source of the pressurized pressure and the bores 14 and 16.Such movement of the piston 26 is transmitted to the operated device(not shown) through the piston rod 50 and the operating arm 52.

H6. 2 illustrates an example of the practical application of the device10 shown in FIG. 1. As shown, the device 10 is incorporated in anautomotive automatic power transmission of a usual type. The powertransmission is shown to comprise a drive shaft 60 and a driven or mainshaft 62. The drive shaft 60 is driven by a suitable prime mover, andthe main shaft 62 is connected to driving wheels (not shown) of thevehicle. The transmission also comprises a turbine shaft 64, and countershafts 66 and 68. The turbine shaft 64 is positioned in line with theshaft 60 and 62 while the counter shaft 66 and 68 are positioned inspaced relation with the shafts 60 and 62. The transmission alsocomprises a hydraulic torque converter 70 with a one-way brake 72, firstand second dog clutches 74 and 76 and a plurality of gears 78, 80, 82,84, 86, 88, 90, 92 and 94.

The hydraulic torque converter 70 comprises, as customary, a pump 70a, aturbine 70b, and a stator 700.

The torque converter 70 operates in a manner well known for driving theturbine 70b.

The first dog clutch 74 includes clutch teeth 74a and 74b, and issplined to a hab(not shown) fixed to the shaft 62. The dog clutch 74 isconnected to a shift rod 98 which in turn is connected to a shift lever100 pivotted at 102. The shift lever 100 is connected to the piston rod50 of the device 10 of this invention so as to move the dog clutch 74into engagement with either the teeth 78a or the teeth 80a. The shiftrod 98 is operatively connected to a shift arm 104 which is adapted tobe controlled manually. The gear 80, which has the clutch teeth 80a, isrotatably mounted on the shaft 62. The gear 82 is fixed on a one-wayclutch 106 rotatable with the shaft 62. The one-way clutch 106 isprovided with clutch teeth 106a which selectively engage with the seconddog clutch 76.

The second dog clutch 76 includes clutch teeth 76a and 76b and isadapted to be moved into engagement with either the teeth 106a or theteeth 84a by controlling a shift rod 108 operatively connected to ashift arm 110. The gear 84, which has the clutch teeth 84a, is rotatablydisposed on the shaft 62.

The gears 86, 88, and 92 are fixed on the counter shaft 66, and are inmesh with the gears 78, 80, 82 and 94, respectively. The gear 94, whichis fixed on the shaft 68, is provided between the gears 84 and 92.

When, in operation, the piston rod 50 of the device 10 is moved to itsintermediate position (see H0. 1 the dog clutch 74 is moved to a neutralposition as shown in FIG. 2. If, in this instance, the dog clutch 76 ismoved, under the control of the shift am 1 10, to a position in whichthe teeth 76a of the dog clutch 76 engages with the teeth 106a connectedto the oneway clutch 106, a low speed power train is established. Theturbine torque built up by the torque converter 70 is then distributedthrough the shaft 64, gears 78 and 86, counter shaft 66, gears 90 and82, one-way clutch 106 and dog clutch 76 to the main shaft 62, whereby areduced gear ratio for the first forward drive is built up.

As the vehicle speed increases, the engine is decelerated. The one-wayclutch 106 then starts free-wheeling, thereby decreasing the rotationalspeed of the gear 82. The rotational speed of the gear 80 also decreasesas the engine is decelerated, whereby the rotational speed of the dogclutch cynchronize with the rotational speed of the gear 80.

If, in this instance, the fluid pressure is drawn only into the bore 16through the port 20 (see FIG. 1), the piston 26 is moved to itsinnermost position so that the piston rod 50 is moved in the samedirection as the piston 26. This causes the shift lever 100 to rotateclockwise, thereby moving the dog clutch 74 to a position in which theteeth 74b engages with the teeth 80a. The power delivered from theturbine shaft 64 is then transmitted through the gears 78 and 86,counter shaft 66, gears 88 and 80, and dog clutch 74 to the main shaft62. An intermediate speed drive ratio is thus established.

As the vehicle speed further increases, the engine is also deceleratedin a manner discussed above. During this deceleration of the engine, thefluid pressure is also drawn into the bore 14 through the port 18 (seeFIG. 1), so that the piston 26 is moved to its intermediate position.Consequently, the dog clutch 74 is set to the neutral position. When theengine speed is decreased so as to synchronize the rotational speed ofthe gear 78 with that of the main shaft 62, the fluid pressure obtainingin the bore 16 is discharged therefrom, whereby the piston 26 is movedto its outermost position. This causes the shift lever 100 to rotatecounterclockwise, thereby moving the dog clutch 74 to a position inwhich the teeth 74a engages with the teeth 78a. The power delivered fromthe turbine shaft 64 is then transmitted through the dog clutch 74 tothe main shaft 62, and thus a high speed drive ratio is established.

It will be apparent that the power transmission described above can becontrolled manually by discharging the fluid pressure from both of thebores 14 and 16 thereby to cause the shift arm 104 to freely move to andesired position.

The application of the device according to this invention as illustratedin FIG. 2 is for illustrative purposes alone and the device disclosedherein may find various practical applications in numerous quarters ofthe industry.

What is claimed is l. A device for selecting three different positions,comprising a hollow body of contoured internal section and having formedtherein first and second bores selectively communicating with a sourceof pressurized fluid, said first bore being larger in cross section thansaid second bore, a first piston having a flange slidably fitted in saidfirst bore and a hollow extension extending from said flange andslidably fitted in said second bore, a first piston ring providedbetween the outer peripheral edge of the flange of said first piston andthe inner wall of said first bore, a second piston having a flangeslidably fitted in said second bore and a hollow extension extendingfrom said flange of said second piston and slidably fitted in the innerperipheral wall of said extension of said first piston, a second pistonring provided between the outer peripheral edge of the flange of saidsecond piston and the inner wall of said second bore, a third pistonring mounted between said hollow extensions of said first and secondpistons, said flange of said first piston having an aperture formedtherein to provide communication between said first bore and theinterior of said hollow extension of said second piston to cause thepressurized fluid admitted to said first bore to act on the inner wallsurface of the flange of said second piston, a drain port communicatingwith a clearance between said hollow extensions of said first and secondpistons to ensure smooth movement of said second piston relative to saidfirst piston, and a piston rod rigidly connected to said flange of saidsecond piston and extending through said second bore outwardly from saidhollow body, said second piston being held in an intermediate positionwhen both of said first and second bores communicate with said source ofthe pressurized fluid to cause both of the flanges of said first andsecond pistons to be subjected to a fluid pressure, said second pistonbeing moved to an innermost position when the communication between saidfirst bore and said source of the pressurized fluid is blocked to causeonly the flange of of said second piston t o be subjected to the fluidpressure and to an outermost positron when the communication betweensaid second bore and said source of the pressurized fluid is blocked tocause only the flange of said second piston to be subjected on its innersurface to the fluid pressure drawn from said first bore through saidaperture, whereby said piston rod is moved to three different positionscorresponding to said innermost, intermediate and outermost positions,of said second piston.

1. A device for selecting three different positions, comprising a hollowbody of contoured internal section and having formed therein first andsecond bores selectively communicating with a source of pressurizedfluid, said first bore being larger in cross section than said secondbore, a first piston having a flange slidably fitted in said first boreand a hollow extension extending from said flange and slidably fitted insaid second bore, a first piston ring provided between the outerperipheral edge of the flange of said first piston and the inner wall ofsaid first bore, a second piston having a flange slidably fitted in saidsecond bore and a hollow extension extending from said flange of saidsecond piston and slidably fitted in the inner peripheral wall of saidextension of said first piston, a second piston ring provided betweenthe outer peripheral edge of the flange of said second piston and theinner wall of said second bore, a third piston ring mounted between saidhollow extensions of said first and second pistons, said flange of saidfirst piston having an aperture formed therein to provide communicationbetween said first bore and the interior of said hollow extension ofsaid second piston to cause the pressurized fluid admitted to said firstbore to act on the inner wall surface of the flange of said secondpiston, a drain port communicating with a clearance between said hollowextensions of said first and second pistons to ensure smooth movement ofsaid second piston relative to said first piston, and a piston rodrigidly connected to said flange of said second piston and extendingthrough said second bore outwardly from said hollow body, said secondpiston being held in an intermediate position when both of said firstand second bores communicate with said source of the pressurized fluidto cause both of the flanges of said first and second pistons to besubjected to a fluid pressure, said second piston being moved to aninnermost position when the communication between said first bore andsaid source of the pressurized fluid is blocked to cause only the flangeof of said second piston to be subjected to the fluid pressure and to anoutermost position when the communication between said second bore andsaid source of the pressurized fluid is blocked to cause only the flangeof said second piston to be subjected on its inner surface to the fluidpressure drawn from said first bore through said aperture, whereby saidpiston rod is moved to three different positions corresponding to saidinnermost, intermediate and outermost positions, of said second piston.